Concerns over maintaining healthy lifestyles continue to grow, and accordingly, vitamin and antioxidant use and intake also continue to rise. As more evidence of the potential benefits associated with the use and intake of vitamins and antioxidants continues to be generated, demand for such substances increases, as does the demand for various forms thereof. Many naturally derived antioxidants and vitamins are normally delivered as oily substances or viscous liquids for encapsulation. However, many potential applications for increased, beneficial consumption and use of such vitamins and antioxidants make solid, free-flowing, and/or powdery formulations more desirable.
For example, some tocopherol compounds such as free tocopherol and tocopheryl acetate, which are oily liquids that exhibit vitamin E activity, can be mixed with carriers and other additives to be made into solids. Other ester forms of tocopherol, such as tocopheryl succinate, are solid. Unfortunately, solid forms of tocopherol such as tocopheryl succinate still do not adequately meet all of the applicational demands necessitated by the various forms of desired vitamin consumption, including, for example, compaction for tableting. Tocopherol compound salts, and in particular, salts of dibasic acid hemiesters of tocopherol, provide tocopherol compounds that exhibit favorable formulation properties. One specific example of such a salt is the calcium salt of tocopherol succinate. However, existing methods for producing such salts from dibasic acid hemiester and calcium starting materials are costly, complicated, and/or inefficient, and thus not widely employed to produce such compounds for use in the vitamin market.
Known processes for producing tocopherol calcium succinate include two step processes wherein a starting material such as tocopherol succinic acid is reacted with lithium hydroxide to produce the lithium salt of tocopherol succinate, which is then reacted with a calcium compound to exchange the lithium ion with a calcium ion. Other processes react tocopherol succinic acid with calcium carboxylates in aqueous solutions to attempt to achieve adequate reaction, but separation of the product from residual carboxylic acid is less than ideal and the reaction is slow.
Thus, there is a need in the art for a process by which tocopherol calcium succinate and other beneficial tocopherol compound salts can be prepared in high yield both quickly and cost-effectively, without undesirable impurities.